287.寻找重复数

😂二分法

class Solution {
public:
    int findDuplicate(vector<int>& nums) {
        sort(nums.begin(), nums.end());
        find(nums, 0, nums.size() - 1);
        return answer;
    }
    void find(vector<int>& nums, int left, int right) {
        if(left > right)
            return ;
        int mid = (left + right ) / 2;
        if(mid - 1 >= 0 && nums[mid - 1] == nums[mid] || mid + 1 <= nums.size() - 1 && nums[mid + 1] == nums[mid])
            answer = nums[mid];
        find(nums, left, mid - 1);
        find(nums, mid + 1, right);
    }
private: 
    int answer;
};

Accepted

53/53 cases passed (20 ms)

Your runtime beats 23 % of cpp submissions

Your memory usage beats 5.07 % of cpp submissions (13.4 MB)